Fungal Defensin Is Potent Antibiotic

A potent peptide antibiotic of the defensin family has been isolated from a mushroom and shown to be as effective as vancomycin and penicillin in curing mice of experimentally induced peritonitis and pneumonia.

Investigators from the University of California, Los Angeles (USA), Georgetown University (Washington, DC, USA), and the biotechnology company Novozymes (Bagsvaerd, Denmark) collaborated on the isolation of the defensin plectasin from the saprophytic ascomycete Pseudoplectania nigrella and subsequently on its large-scale production using recombinant techniques.

They reported in the October 13, 2005, issue of Nature that the recombinant form of plectasin was especially active against Streptococcus pneumoniae, including strains resistant to conventional antibiotics. They found that the structure of plectasin was remarkably similar to the defensins of spiders, scorpions, dragonflies, and ticks, which suggested that the defensins of insects, mollusks, and fungi arose from a common ancestral gene that probably existed over a billion years ago.

"Most antibiotics used by humans are produced by fungi and certain soil bacteria,” said contributing author Dr. Michael Zasloff, professor of pediatric surgery at Georgetown University Medical Center. "Using our existing tools of discovery, we have failed to uncover any new classes of antibiotics from these sources over the past decade. However, by utilizing a new genetic approach that allowed the team to discover plectasin, we now know that a whole class of antibiotics has been overlooked.”




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University of California, Los Angeles
Georgetown University
Novozymes